[{quoted}](name=The Bearded Bard,realm=NA,application-id=3ErqAdtq,discussion-id=Zgq7eFhb,comment-id=0004,timestamp=2015-11-20T10:23:57.137+0000)
Probably because she's not a mid laner, she's a top laner.
Come on, you've got to be blind not to see it. She was made to destroy top laners.
Juggernauts?
Never gonna get anywhere near her. She's gonna hammer them from afar with mantra'd Q's, snare them with ease when they charge in, shield away in the event that those two fail.
Top lane mages? 
All have too little range to deal with Karma.
Tanks?
Her disengage and sustain is too strong for them to kill her.
As a top laner, she excels at dueling during lane phase and being very near ungankable if played well. Late game she's fantastic at keeping her teammates alive, setting up fights, catching out lone enemies, poking, disengaging, engaging, and providing damage. She's also great at locking down stealth champs and mobile champs with W.
Personally, I think she's a fine champions, very versatile and fun to play. Easily one of my best and favorite champions in this game.
Those juggernauts you listed never even have to chase you,they really don't need to interact with you at all because of their sustain
If you're actually played against any of those mages you'd know they do way more damage and she doesn't have a chance in hell at killing the mages with sustain
Again these Tanks that can't kill her REALLY do not need to Karma has no chance in killing them either while they scale into the game while Karma falls off because her mid range isn't usable late game not to mention she wont have any kills
She's always been a good laner,but that's literally it PLENTY of champions have a good laning phase AND Late game while Karma lacks any as she's reduced to an AOE shield bot which contrary to popular belief is one of the WORST speed buffs in the game and is really oversold by people that don't know what they're talking about.
Not to mention you yourself are negative with Karma